The torque from the engine of a motor vehicle is transmitted via a main drive shaft normally including one or more flexible couplings or universal joints to a differential from which the power is fed through a pair of wheel drive-shafts to the motor-vehicle wheels. A transmission is provided normally at the output of the engine or even immediately upstream of the differential.
The problem with such drive systems is that vibrations in the audio range are transmitted along the drive system to the vehicle wheels, and thence through the suspension for these wheels to the body of vehicle. As a result the noise level inside the vehicle is increased considerably. Such transmission of vibriations is aggravated by the so-called bending resonance of the torque-transmission elements.
Systems, such as seen in German Patent Publication No. 2,156,783, have been designed for allowing the drive-shaft assembly to absorb axial stresses through plastic deformation of an element, but these arrangements still do not in any manner damp vibrations through the system. Other arrangements are known which incorporate elastic elements into the force-transmission path between the engine and the wheels. All these such systems normally result in some loss of torque and have a relative short service life. In fact the amount of vibrations transmitted is normally inversely proportional to the amount of torsional energy that is lost in such systems.